The coefficient \(c_B^{\rm sph}\)  in Eq. (REF ), finally, accounts for the evolution of the weak mixing angle \(\theta _{\rm w}\left(T\right)\)  [1]},
\(c_B^{\rm dec} = \frac{17}{37} \left(1 + \frac{g_L^2}{g_Y^2}\right) \frac{H\,\Theta }{\Gamma _{\rm ws}}\,, \qquad \Theta = -T\,\frac{d \theta _{\rm w}}{dT}\,\sin \left(2\theta _{\rm w}\right) \,,\) 
